A method and apparatus for scanning the surface of the motor vehicle wheel by using a light beam emitted by a light source, and a position-sensitive receiver for detecting the reflected beam, are discussed in U.S. Pat. No. 6,535,281, titled “METHOD AND APPARATUS FOR OPTICALLY SCANNING A VEHICLE WHEEL,” the entire disclosure of which is incorporated herein by reference. The spacing of the scanned location relative to a reference location is measured based on the directions of the emitted beam and the reflected beam, wherein the light source and the position-sensitive receiver pivot together about a common axis by means of a rotary drive for successive measuring steps.
This disclosure describes an improved method and apparatus for ascertaining geometrical parameters of the vehicle wheel and its constituent parts. A vehicle wheel is rotatably mounted to a stationary axis, such as a measuring shaft of a wheel balancer. The wheel is scanned by one or more light beams, such as laser beams. A light beam is directed from at least one given position onto the surface of the vehicle wheel. The light beam is then reflected by the vehicle wheel surface and received by at least one receiver installed at least one given position. Dimensions and/or positions of constituent parts of the vehicle wheel, such as the wheel disc portion, the rim, the rim flange or the pneumatic tire, are ascertained in a computer-aided procedure based on the direction of the emitted light beam and the reflected light beam.
The rim profile can be detected using the optical scanning operation on both side surfaces of the wheel. The type of wheel or the type of disc wheel portion can be ascertained based on a result of the scanning operation. In addition, the rim flanges as well as the material thickness of the wheel disc portion and the rim can also be determined using the scanning operation. Light beams are directed onto both sides of the vehicle wheel. The respective reflected beams are detected. One or more sensor devices including both a light source for emitting a light beam and a receiver for receiving the reflected beam are used. The light source and the receiver are arranged in such a way that the sensor can detect both sides of the vehicle wheel. Alternatively, two sensor devices may be provided, one for detecting the inside of the wheel and the other for detecting the outside of the wheel.
In addition, when scanning the rim from the rear side of the wheel and/or the outside of the wheel, whether one or more balancing weights are secured to the rim can be determined by the scanning process. The scanning process also determines the position of the respective balancing weight.
In one embodiment, the position, in particular the rotary angle position of a tire valve with which the pneumatic tire of the motor vehicle wheel is inflated, is detected by, for example, using the scanning process. That valve position may be used as a reference position (zero position) in a rotary angle detection procedure on the motor vehicle wheel.
In conjunction with detecting wheel spokes by using the optical light scanning procedure, the valve position can be used as a reference position for detecting the rotary angle positions of the various spokes on the motor vehicle wheel. The scanning procedure is performed to detect the positions and dimensions of the ends of the spokes at the rim. Knowledge of those positions and dimensions facilitates placement of the balancing weights behind spokes.
Additional aspects and advantages of the present disclosure will become readily apparent to those skilled in this art from the following detailed description, wherein only exemplary embodiments of the present disclosure is shown and described, simply by way of illustration of the best mode contemplated for carrying out the present disclosure. As will be realized, the present disclosure is capable of other and different embodiments, and its several details are capable of modifications in various obvious respects, all without departing from the disclosure. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not as restrictive.